In this third year of longitudinal study of behavioral effects of exposure to inorganic mercury, industrial will continue to be tested using objective tremor, electromyographic, psychomotor, and short term memory tests. Primary emphasis is on detection of functional changes in workers who newly enter mercury exposure jobs, or transfer from exposure jobs to jobs in non-exposure areas. Workers who have thus been exposed to mercury and controls are tested at two mercury cell Chlor-alkali plants at three month intervals. In previous work, frequency spectra obtained from measurement of forearm sustension tremor have been most sensitive in detecting early subclinical effects of mercury exposure. These effects have been found to be reversible upon removing the worker from mercury exposure. Thus research has the primary goal of demonstrating the use of behavioral testing methods in the medical management of workers exposed to inorganic mercury. In this final year, data will be analyzed with the goal of providing guidelines based on urinary mercury and behavioral test results which will provide protection against potential neurological effects of mercury exposure.